Process for the continuous gas-phase (co-) polymerisation of olefins in a fluidized bed reactor

ABSTRACT

A process for the continuous gas-phase (co-)polymerisation of olefins in a fluidised bed reactor using a Ziegler-Nata type catalyst wherein the polymerisation is performed in the presence of a process aid additive selected from at least one of (1) a polysulphone copolymer; (2) a polymeric polyamine or (3) an oil-soluble sulphonic acid.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of international application numberPCT/GB00/03401, filed Sep. 5, 2000, the content of which is incorporatedherein by reference, and claims the priority of European PatentApplication No. 99430018.4, filed Sep. 9, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to a process for the continuous gas-phase(co-)polymerisation of olefins in a fluidised bed reactor using aZiegler-Natta type catalyst.

The present invention also relates to a process for preventing foulingduring the continuous gas-phase (co-)polymerisation of olefins in afluidised bed reactor using a Ziegler-Natta type catalyst.

Processes for the co-polymerisation of olefins in the gas phase are wellknown in the art. Such processes can be conducted for example byintroducing the gaseous monomer and comonomer into a stirred and/or gasfluidised bed comprising polyolefin and a catalyst for polymerisation.

In the gas fluidised bed polymerisation of olefins, the polymerisationis conducted in a fluidised bed reactor wherein a bed of polymerparticles is maintained in a fluidised state by means of an ascendinggas stream comprising the gaseous reaction monomer. The start-up of sucha polymerisation generally employs a bed of polymer particles similar tothe polymer which it is desired to manufacture. During the course ofpolymerisation, fresh polymer is generated by the catalyticpolymerisation of the monomer, and polymer product is withdrawn tomaintain the bed at more or less constant volume. An industriallyfavoured process employs a fluidisation grid to distribute thefluidising gas to the bed, and to act as a support for the bed when thesupply of gas is cut off. The polymer produced is generally withdrawnfrom the reactor via a discharge conduit arranged in the lower portionof the reactor, near the fluidisation grid. The fluidised bed consistsin a bed of growing polymer particles. This bed is maintained in afluidised condition by the continuous upward flow from the base of thereactor of a fluidising gas.

The polymerisation of olefins is an exothermic reaction and it istherefore necessary to provide means to cool the bed to remove the heatof polymerisation. In the absence of such cooling the bed would increasein temperature and, for example, the catalyst would become inactive orthe bed would begin to melt. In the fluidised bed polymerisation ofolefins, the preferred method for removing the heat of polymerisation isby supplying to the polymerisation reactor a gas, the fluidising gas,which is at a temperature lower than the desired polymerisationtemperature, passing the gas through the fluidised bed to conduct awaythe heat of polymerisation, removing the gas from the reactor andcooling it by passage through an external heat exchanger, and recyclingit to the bed. The temperature of the recycle gas can be adjusted in theheat exchanger to maintain the fluidised bed at the desiredpolymerisation temperature. In this method of polymerising alphaolefins, the recycle gas generally comprises the monomer and comonomerolefins, optionally together with, for example, an inert diluent gassuch as nitrogen or a gaseous chain transfer agent such as hydrogen.Thus, the recycle gas is used to supply the monomer to the bed, tofluidise the bed, and to maintain the bed at the desired temperature.Monomers consumed by the polymerisation reaction are normally replacedby adding make up gas or liquid to the polymerisation zone or reactionloop.

It is well known that Ziegler-Natta type catalysts can advantageously beused for the (co-)polymerisation of olefins, particularly in slurryprocesses as well as in gas phase processes. It is also reported in theliterature that these catalysts are prone to fouling problems in olefingas phase polymerisation processes. While the man in the art specialisedin olefin gas phase polymerisation has made a lot of progresses in theunderstanding of the fouling phenomena associated with the use ofZiegler-Natta catalysts, there is still a need in the art to find aprocess for producing more successfully polyolefins on gas phaseindustrial plants using such a Ziegler-Natta type catalyst.

The Applicants have now unexpectedly found a simple and efficientprocess which allows us to improve the gas phase polymerisation ofolefins using a Ziegler-Natta type catalyst. This was done through adetailed analysis of the rare problems occurring during the olefin gasphase polymerisation using a Ziegler-Natta type catalyst. Amongst thoseproblems, one can recite slight fouling which can repeatedly occurduring polymerisation and provoke periods of off specificationmaterials, fouled lumps, . . . ; hot spot phenomena related to points ofhigher than average temperature within the polymerisation zone; staticphenomena measured with static probes within the polymerisation zonewere also part of the detailed analysis and study.

Surprisingly, the very simple process of the Applicants provides anindustrial solution to all these problems, in particular to the foulingproblems that could affect gas phase polymerisation of olefins withZiegler-Natta type catalysts.

SUMMARY OF THE INVENTION

In accordance with the present invention, there has now been found aprocess for the gas-phase (co-)polymerisation of olefins in a fluidisedbed reactor using a Ziegler-Natta type catalyst in the presence of aprocess aid additive wherein the additive comprises at least one of thecomponents selected from:

(1) a polysulphone copolymer,

(2) a polymeric polyamine, and

(3) an oil-soluble sulphonic acid.

Preferably, the process aid additive comprises at least two componentsselected from above components (1), (2) and (3). More preferably, theprocess aid additive comprises a mixture of (1), (2) and (3).

DETAILED DESCRIPTION OF THE INVENTION

The process aid additive can be added at any location of the fluidisedbed polymerisation system, e.g. in the reactor itself, below thefluidisation grid or above the grid in the fluidised bed, above thefluidised bed, in the powder disengagement zone of the reactor (alsonamed velocity reduction zone), anywhere in the reaction loop or recycleline, in the fines recycle line (when a fines separator, preferably acyclone, is used), etc . . . According to a preferred embodiment of thepresent invention, the process aid additive is directly added into thefines recycle line (when a fines separator, preferably a cyclone, isused), or directly into the polymerisation zone, more preferablydirectly into the fluidised bed, ideally into the lower part of the bed(below half bed height). For the purposes of the present invention andappended claims, the polymerisation zone means the reaction zoneconsisting of the fluidised bed itself, and the region above thefluidised bed which consists of the powder disengagement zone and/or thevelocity reduction zone. According to another preferred embodiment ofthe present invention, the process aid additive is added at at least twodifferent locations of the fluidised bed polymerisation system. It isalso particularly preferred according to the present invention that theprocess aid additive is not added in admixture with a catalyst componentlike the catalyst itself or the cocatalyst. According to anotherpreferred embodiment, the process aid additive is added into thefluidised bed polymerisation system through the well known BP highproductivity nozzles which protrude through the fluidisation griddirectly into the fluidised bed (see e.g. W09428032, the content ofwhich is incorporated hereby). It may also be preferred that the processaid additive is not added in admixture with a liquid comonomer used forthe copolymerisation.

According to the present invention, the polysulphone copolymer componentof the process aid additive (often designated as olefin-sulphur dioxidecopolymer, olefin polysulphones, or poly(olefin sulphone)), is apolymer, preferably a linear polymer, wherein the structure isconsidered to be that of alternating copolymers of the olefins andsulphur dioxide, having a one-to-one molar ratio of the comonomers withthe olefins in head to tail arrangement. Preferably, the polysulphonecopolymer consists essentially of about 50 mole percent of units ofsulphur dioxide, about 40 to 50 mole percent of units derived from oneor more 1-alkenes each having from about 6 to 24 carbon atoms, and fromabout 0 to 10 mole percent of units derived from an olefinic compoundhaving the formula ACH═CHB where A is a group having the formula—(C_(x)H_(2x))—COOH wherein x is from 0 to about 17, and B is hydrogenor carboxyl, with the proviso that when B is carboxyl, x is 0, andwherein A and B together can be a dicarboxylic anhydride group.

Preferably, the polysulphone copolymer employed in the present inventionhas a weight average molecular weight in the range 10,000 to 1,500,000,preferably in the range 50,000 to 900,000. The units derived from theone of more 1-alkenes are preferably derived from straight chain alkeneshaving 6-18 carbon atoms, for example 1-hexene, 1-heptene, 1-octene,1-decene, 1-dodecene, 1-hexadecene and 1-octadecene. Examples of unitsderived from the one or more compounds having the formula ACH═CHB areunits derived from maleic acid, acrylic acid, 5-hexenoic acid. Forfurther details of polysulphones particularly suitable for use in thepresent invention reference may be made to UK patent specifications1,432,265, 1,432,266, and U.S. Pat. Nos. 3,811,848 and 3,917,466.

A preferred polysulphone copolymer is 1-decene polysulphone having aninherent viscosity (measured as a 0.5 weight percent solution in tolueneat 30° C.) ranging from about 0.04 dl/g to 1.6 dl/g.

According to the present invention, the polymeric polyamine component ofthe process aid additive is preferably a polymeric polyamine having thegeneral formula:

RN[(CH₂CHOHCH₂NR¹)_(a)—(CH₂CHOHCH₂NR¹—R²—NH)_(b)—(CH₂CHOHCH₂NR³)_(c)H]_(x)H_(2-x),

wherein R¹ is an aliphatic hydrocarbyl group of 8 to 24 carbon atoms,

R² is an alkylene group of 2 to 6 carbon atoms,

R³ is the group —R²—HNR¹,

R is R¹ or an N-aliphatic hydrocarbyl alkylene group having the formulaR¹NHR²—;

a, b and c are integers of 0-20 and x is 1 or 2; with the proviso thatwhen R is R¹ then a is an integer of 2 to 20 and b=c=0, and when R isR¹NHR²— then a is 0 and b+c is an integer of 2 to 20.

The polymeric polyamines which can be suitably employed in the processof the present invention are described in U.S. Pat. No. 3,917,466, inparticular at column 6 line 42 to column 9 line 29.

The polymeric polyamine may be prepared for example by heating analiphatic primary monoamine or N-aliphatic hydrocarbyl alkylene diaminewith epichlorohydrin in the molar proportion of from 1:1 to 1:1.5 at atemperature of 50° C. to 100° C. in the presence of a solvent, eg amixture of xylene and isopropanol, adding a strong base, eg sodiumhydroxide and continuing the heating at 50 to 100° C. for about 2 hours.The product containing the polymeric polyamine may then be separated bydecanting and then flashing off the solvent.

The polymeric polyamine is preferably the product of reacting anN-aliphatic hydrocarbyl alkylene diamine or an aliphatic primary aminecontaining at least 8 carbon atoms and preferably at least 12 carbonatoms with epichlorohydrin. Examples of such aliphatic primary aminesare those derived from tall oil, tallow, soy bean oil, coconut oil andcotton seed oil. The polymeric polyamine derived from the reaction oftallowamine with epichlorohydrin is preferred. A method of preparingsuch a polyamine is disclosed in U.S. Pat. No. 3,917,466, column 12,preparation B.1.0

The above-described reactions of epichlorohydrin with amines to formpolymeric products are well known and find extensive use in epoxideresin technology.

A preferred polymeric polyamine is a 1:1.5 mole ratio reaction productof N-tallow-1,3-diaminopropane with epichlorohydrin. One such reactionproduct is “Polyflo 130” sold by Universal Oil Company.

According to the present invention, the oil-soluble sulphonic acidcomponent of the process aid additive is preferably any oil-solublesulphonic acid such as an alkane sulphonic acid or an alkylarylsulphonic acid. A useful sulphonic acid is petroleum sulphonic acidresulting from treating oils with sulphuric acid.

Preferred oil-soluble sulphonic acids are dodecylbenzene sulphonic acidand dinonylnaphthyl sulphonic acid.

In accordance with the present invention, the process aid additivepreferably comprises 1 to 25 weight percent of the polysulphonecopolymer, 1 to 25 weight percent of the polymeric polyamine, 1 to 25weight percent of the oil-soluble sulphonic acid and 25 to 95 weightpercent of a solvent. Neglecting the solvent, the process aid additivepreferably comprises about 5-70 weight percent polysulphone copolymer,5-70 weight percent polymeric polyamine, and 5-70 weight percentoil-soluble sulphonic acid; the total of course being 100 percent.

Suitable solvents include aromatic, paraffin and cycloparaffincompounds.

The solvents are preferably selected from among benzene, toluene,xylene, cyclohexane, fuel oil, isobutane, kerosene and mixtures thereoffor instance.

According to a preferred embodiment of the present invention, theprocess aid additive is diluted in a conventional hydrocarbon diluent,which can be the same or different from the above solvent, preferablybutane, pentane or hexane.

When a diluent is used, the process aid additive (including the solventthereof) is preferably present in an amount comprised between 0.1 and500 g per liter of diluent, preferably between 1 and 50 g per liter ofdiluent.

According to a preferred embodiment of the present invention, the totalweight of components (1), (2), (3), the solvent and the diluentrepresents essentially 100% of the weight of the process aid additive.

One useful composition, for example, consists of 13.3 weight percent 1:1copolymer of 1-decene and sulphur dioxide having an inherent viscosityof 0.05 determined as above, 13.3 weight percent of “Polyflo 130” (1:1.5mole ratio reaction product of N-tallow-1,3-diaminopropane withepichlorohydrin), 7.4 weight percent of either dodecylbenzene sulphonicacid or dinonylnaphthyl sulphonic acid, and 66 weight percent of anaromatic solvent which is preferably toluene or kerosene.

Another useful composition, for example, consists of 2 to 7 weightpercent 1:1 copolymer of 1-decene and sulphur dioxide having an inherentviscosity of 0.05 determined as above, 2 to 7 weight percent of “Polyflo130” (1:1.5 mole ratio reaction product of N-tallow-1,3-diaminopropanewith epichlorohydrin), 2 to 8 weight percent of either dodecylbenzenesulphonic acid or dinonylnaphthyl sulphonic acid, and 78 to 94 weightpercent of an aromatic solvent which is preferably a mixture of 10 to 20weight percent toluene and 62 to 77 weight percent kerosene.

The additive composition of the present invention (including the solventand diluent therefor) is preferably added to the reactor in an amountranging from about 0.02 to about 50000 ppm, preferably from about 0.2 toabout 10000 ppm, more preferably from about 2 to 1000 ppm, based on theweight of the olefin introduced into the reactor.

Based on the total weight of just the polysulphone polymer, polymericamine and oil-soluble sulphonic acid, the preferred concentration of theaid additive is from about 0.00001 to about 35, preferably from about0.0001 to about 7.5, more preferably from about 0.006 to about 4 partsby weight per million parts by weight of the olefin introduced into thereactor.

The process aid additive can be added continuously or intermittently tothe reactor. In the continuous gas phase polymerisation processaccording to the present invention, it is preferred to add continuouslythe additive to the reactor. Sufficient process aid additive is added tomaintain its concentration at the desired level.

According to a preferred embodiment of the present invention, before theZiegler-Natta type catalyst is introduced into the reactor, the reactoris pre-loaded with the said process aid additive. This pre-load can bedone before or after the introduction of the seed bed polymer into thereactor; however, it is preferred to perform the pre-load solely on theseed bed polymer.

For the pre-load, the additive composition of the present invention(including the solvent and diluent therefor) is preferably added to thereactor in an amount ranging from about 0.02 to about 50000 ppm,preferably from about 0.2 to about 10000 ppm, more preferably from about2 to 1000 ppm, based on the weight of the seed polymer bed.

Based on the total weight of just the polysulphone polymer, polymericamine and oil-soluble sulphonic acid, the preferred concentration of theaid additive is from about 0.00001 to about 35, preferably from about0.0001 to about 7.5, more preferably from about 0.006 to about 4 partsby weight per million parts by weight of the seed polymer bed.

According to a preferred embodiment of the present invention, theprocess aid additive is a material sold by Octel under the trade nameSTADIS, preferably STADIS 450, more preferably STADIS 425, said STADIScomponents being preferably added at a rate of 0.001 to 50 ppm by weightof the olefin introduced into the reactor and/or at a concentration of0.01 to 10 ppm by weight of the seed polymer bed in case of pre-load.

In accordance with the present invention, there is also provided aprocess for preventing fouling during the gas-phase (co-)polymerisationof olefins in a fluidised bed reactor using a Ziegler-Natta typecatalyst in the presence of a process aid additive characterised in thatthe additive comprises a mixture of

(1) a polysulphone copolymer,

(2) a polymeric polyamine, and

(3) an oil-soluble sulphonic acid.

The process according to the present invention is suitable for themanufacture of polymers in a continuous gas fluidised bed process.

In an advantageous embodiment of this invention, the polymer is apolyolefin preferably copolymers of ethylene and/or propylene and/orbutene. Preferred alpha-olefins used in combination with ethylene and/orpropylene and/or butene in the process of the present invention arethose having from 4 to 8 carbon atoms. However, small quantities ofalpha olefins having more than 8 carbon atoms, for example 9 to 40carbon atoms (e.g. a conjugated diene), can be employed if desired. Thusit is possible to produce copolymers of ethylene and/or propylene and/orbutene with one or more C4-C8 alpha-olefins. The preferred alpha-olefinsare but-1-ene, pent-1-ene, hex-1-ene, 4-methylpent-1-ene, oct-1-ene andbutadiene. Examples of higher olefins that can be copolymerised with theprimary ethylene and/or propylene monomer, or as partial replacement forthe C4-C8 monomer are dec-1-ene and ethylidene norbornene. According toa preferred embodiment, the process of the present invention preferablyapplies to the manufacture of polyolefins in the gas phase by thecopolymerisation of ethylene with but-1-ene and/or hex-1-ene and/or4-methylpent-1-ene.

The process according to the present invention may be used to prepare awide variety of polymer products for example linear low densitypolyethylene (LLDPE) based on copolymers of ethylene with but-1-ene,4-methylpent-1-ene or hex-1-ene and high density polyethylene (HDPE)which can be for example copolymers of ethylene with a small portion ofhigher alpha olefin, for example, but-1-ene, pent-1-ene, hex-1-ene or4-methylpent-1-ene.

When liquid condenses out of the recycle gaseous stream, it can be acondensable monomer, e.g. but-1-ene, hex-1-ene, 4-methylpent-1-ene oroctene used as a comonomer, and/or an optional inert condensable liquid,e.g. inert hydrocarbon(s), such as C4-C8 alkane(s) or cycloalkane(s),particularly butane, pentane or hexane.

The process is particularly suitable for polymerising olefins at anabsolute pressure of between 0.5 and 6 MPa and at a temperature ofbetween 30° C. and 130° C. For example for LLDPE production thetemperature is suitably in the range 75-90° C. and for HDPE thetemperature is typically 80-112° C. depending on the activity of thecatalyst used and the polymer properties desired.

The polymerisation is preferably carried out continuously in a verticalfluidised bed reactor according to techniques known in themselves and inequipment such as that described in European patent application EP-0 855411, French Patent No. 2,207,145 or French Patent No. 2,335,526. Theprocess of the invention is particularly well suited to industrial-scalereactors of very large size.

In one embodiment the reactor used in the present invention is capableof producing greater than 300 Kg/hr to about 80,000 Kg/hr or higher ofpolymer, preferably greater than 10,000 Kg/hr.

The polymerisation reaction is carried out in the presence of aZiegler-Natta type catalyst.

Examples of Ziegler-Natta type catalysts according to the presentinvention are typically those consisting of a solid catalyst essentiallycomprising a compound of a transition metal and of a cocatalystcomprising an organic compound of a metal (i.e. an organometalliccompound, for example an alkylaluminium compound). These high-activityZiegler-Natta type catalyst systems have already been known for a numberof years and are capable of producing large quantities of polymer in arelatively short time, and thus make it possible to avoid a step ofremoving catalyst residues from the polymer. These high-activitycatalyst systems generally comprise a solid catalyst consistingessentially of transition metal complexes, magnesium complexes andhalogen containing complexes. Examples thereof can be found, e.g. inU.S. Pat. No. 4,260,709, EP0598094, EP0099774 and EP0175532. The processis also particularly suitable for use with Ziegler catalysts supportedon silica, e.g. in WO9309147, WO9513873, WO9534380 and WO9905187. Forthe purpose of the present description and appended claims,Ziegler-Natta type catalysts specifically exclude the metallocenecatalysts.

The catalyst can be used as it is or optionally in the form of a coatedcatalyst or prepolymer containing, for example, from 10⁻⁵ to 3,preferably from 10⁻³ to 10⁻¹, millimoles of transition metal per gram ofpolymer. The process of the invention is particularly suited to the useof a non-prepolymerized catalyst, preferably to the direct introductionof a Ziegler-Natta supported catalyst, more preferably a silicasupported titanium containing Ziegler-Natta catalyst.

The Ziegler-Natta type catalysts used in the present invention may beused together with a cocatalyst or activator, e.g. an organometalliccompound of a metal from groups I to III of the Periodic Classificationof the Elements, such as, for example, an organoaluminum compound.

The following non limiting examples illustrate the present invention.

EXAMPLE 1

The catalyst is a silica supported catalyst which is the same as the onedisclosed in example E1 of WO9513873; excepted that the silica supporthas been thermally treated at a temperature of 700° C. (instead of 600°C.) which gives a final OH content of 0.52.

The process is carried out in a fluidised bed gas phase polymerisationreactor consisting of a vertical cylinder of diameter 0.74 m and height7 m and surmounted by a velocity reduction chamber. In its lower part,the reactor is equipped with a fluidisation grid and an external linefor recycling gas, connecting the top of the velocity reduction chamberto the lower part of the reactor, situated under the fluidisation grid.The gas recycling line is equipped with a compressor and with a heattransfer means. Opening into the gas recycling line there are, inparticular, the feed lines for ethylene, 1-hexene and nitrogen whichrepresent the main constituents of the gas reaction mixture passingthrough the fluidised bed.

Above the fluidisation grid the reactor contains a fluidised bedconsisting of a medium density polyethylene powder. The gas reactionmixture, which contains ethylene, 1-hexene, hydrogen, pentane andnitrogen passes through the fluidised bed at a pressure of 2 MPa, at 93°C. and with an upward fluidisation velocity of 0.55 m/s.

The gas phase is composed with 0.8 MPa of ethylene, and molar ratio ofhydrogen to ethylene at 0.18; hexene-1 to ethylene partial pressure at0.08.

The catalyst is introduced into the reactor, at a rate of 20 g/h;simultaneously a solution of triethylaluminium diluted in pentane at aconcentration of 0.5 moles of TEA/liter of pentane, is injected at 0.75liter/h.

No process aid additive is injected.

Since the start-up and until when the production rate reaches 180 kg/h,hot spots started rapidly to appear on the internal penetratingtemperature probes, as well as on the skin temperature probes located inthe 0.8 to 1.2 m (above the fluidisation grid) zone of the reactor.

It was then decided to introduce STADIS 425 into the reactor. It ispreviously diluted in pentane in a ratio of 7 g of STADIS 425 per literof pentane.

The solution of STADIS 425 was injected into the polymerisation reactorat 1 meter above the grid at flow rate of 0.2 l of diluted Stadis perhour. Within 5 minutes all the temperature probes became much morestable. No agglomerates were produced, while production rate could thenbe safely increased to 230 kg/h.

A flowability measurement made on the polyethylene before and after theaddition of STADIS revealed a much better value obtained by applying thepresent invention. The present invention consequently also relates to aprocess for improving the polymer flowability and the fluidisationcharacteristics during the gas-phase (co-)polymerisation of olefins in afluidised bed reactor using a Ziegler-Natta catalyst.

At the end of the run, the reactor was opened/inspected and revealed noindication of fouling, i.e. the reactor wall (the cylindrical section aswell as the bulb) was perfectly clean.

EXAMPLE 2

The process is carried out in the same reactor as in example 1 and withthe same catalyst system.

Above the fluidisation grid the reactor contains a fluidised bedconsisting of a medium density polyethylene powder. The gas reactionmixture, which contains ethylene, 1-hexene, hydrogen, pentane andnitrogen passes through the fluidised bed at a pressure of 2 MPa, at102° C. and with an upward fluidisation velocity of 0.55 m/s.

The gas phase is composed with 0.8 MPa of ethylene, and molar ratio ofhydrogen to ethylene at 0.13; hexene-1 to ethylene partial pressure at0.08.

The catalyst is introduced into the reactor, at a rate of 20 g/h;simultaneously a solution of triethylaluminium diluted in pentane at aconcentration of 0.5 moles of TEA/liter of pentane, is injected at 0.75liter/h.

No process aid additive is injected.

Since the start-up and until when the production rate reaches 200 kg/h,hot spots started rapidly to appear on the internal penetratingtemperature probes, as well as on the skin temperature probes located inthe 0.8 to 1.2 m (above the fluidisation grid) zone of the reactor.

It was then decided to introduce STADIS 425 into the reactor. It ispreviously diluted in pentane in a ratio of 1 g of STADIS 425 per literof pentane.

The solution of STADIS 425 was injected into the polymerisation reactorat 1 meter above the grid at flow rate of 0.2 l of diluted Stadis perhour. Within 5 minutes all the temperature probes became much morestable. No agglomerates were produced, while production rate could thenbe safely increased to 230 kg/h.

At the end of the run, the reactor was opened/inspected and revealed noindication of fouling, i.e. the reactor wall (the cylindrical section aswell as the bulb) was perfectly clean.

What is claimed is:
 1. A process for the continuous gas-phase(co-)polymerisation of olefins comprising (co-)polymerising one or moreolefins in a polymerisation zone of a fluidised bed reactor using aZiegler-Natta type catalyst in the presence of a process aid additive,wherein the additive comprises at least one of the components selectedfrom the group consisting of (1) a polysulphone copolymer, (2) apolymeric polyamine, and (3) an oil-soluble sulphonic acid and whereinthe process aid additive represents from about 0.00001 to about 35 partsby weight per million parts by weight of olefin introduced into thereactor.
 2. Process according to claim 1 wherein the process aidadditive is directly added into the polymerisation zone.
 3. Processaccording to claim 2 wherein the process aid additive is directly addedinto the fluidised bed polymerisation reaction zone.
 4. Processaccording to claim 1 wherein the process aid additive is not added inadmixture with the catalyst or a cocatalyst.
 5. Process according toclaim 1 wherein the process aid additive comprises at least twocomponents selected from components (1), (2) or (3).
 6. Processaccording to claim 5 wherein the process aid additive comprises amixture of components (1), (2) and (3).
 7. Process according to claim 6wherein the process aid additive comprises about 5-70 weight percentpolysulphone copolymer, 5-70 weight percent polymeric polyamine, and5-70 weight percent oil-soluble sulphonic acid.
 8. Process according toclaim 1 wherein the reactor is preloaded with the process aid additivebefore the Ziegler-Natta type catalyst is introduced into the reactor.9. Process according to claim 8 wherein the pre-load is performed onseed bed polymer.
 10. Process according to claim 1 wherein the one ormore olefins is ethylene or propylene.
 11. Process according to claim 1wherein the one or more olefins are ethylene or propylene and one ormore comonomers selected from the group consisting of but-1-ene,pent-1-ene, hex-1-ene, 4-methylpent-1-ene, and oct-1-ene.
 12. Processaccording to claim 11 wherein the one or more olefins are ethylene andthe one or more comonomers is selected from but-1-ene, hex-1-ene, or4-methylpent-1-ene.
 13. Process according to claim 1 wherein the processaid additive represents from about 0.0001 to about 7.5 parts by weightper million parts by weight of olefin introduced into the reactor. 14.Process according to claim 13 wherein the process aid additiverepresents about 0.006 to about 4 parts by weight per million parts byweight of olefin introduced into the reactor.
 15. A process for thecontinuous gas-phase (co-)polymerisation of olefins comprising(co-)polymerising ethylene and one or more comonomers selected frombut-1-ene, hex-1-ene or methylpent-1-ene in a polymerisation zone of afluidised bed reactor using a Ziegler-Natta type catalyst in thepresence of a process aid additive, wherein the additive comprises atleast one of the components selected from the group consisting of (1) apolysulphone copolymer, (2) a polymeric polyamine, and (3) anoil-soluble sulphonic acid.
 16. Process according to claim 15 whereinthe process aid additive is directly added into the polymerisation zone.17. Process according to claim 16 wherein the process aid additive isdirectly added into the fluidised bed polymerization reaction zone. 18.Process according to claim 15 wherein the process aid additive is notadded in admixture with the catalyst or a cocatalyst.
 19. Processaccording to claim 15 wherein the process aid additive comprises atleast two components selected from components (1), (2) or (3). 20.Process according to claim 19 wherein the process aid additive comprisesa mixture of components (1), (2) and (3).
 21. Process according to claim20 wherein the process aid additive comprises about 5-70 weight percentpolysulphone copolymer, 5-70 weight percent polymeric polyamine, and5-70 weight percent oil-soluble sulphonic acid.
 22. Process according toclaim 15 wherein the process aid additive represents from about 0.00001to about 35 parts by weight per million parts by weight of olefinintroduced into the reactor.
 23. Process according to claim 22 whereinthe process aid additive represents from about 0.0001 to about 7.5 partsby weight per million parts by weight of olefin introduced into thereactor.
 24. Process according to claim 23 wherein the process aidadditive represents from about 0.006 to about 4 parts by weight permillion parts by weight of olefin introduced into the reactor. 25.Process according to claim 15 wherein the reactor is preloaded with theprocess aid additive before the Ziegler-Natta type catalyst isintroduced into the reactor.
 26. Process according to claim 23 whereinthe pre-load is performed on seed bed polymer.